I've been running my SYA kit for a while now too and that's when I added the push to connect fittings and extra tubing. I added it, because it was convenient to do it at the time. So, I'd agree with @avslash that it's really not a huge concern if you're using 6mm all the way.FWIW, mine has been setup this way, with the addition of four additional connectors when I added the SYA spacers for a minimum of 6 years.
I have never had an issue with any of the additional connectors. Literally, zero.
Just had my first air system related issue in a decade of ownership, and it was the center valve block. Those extra connectors in the system are still chugging along.
For anyone thinking 1/4" (0.25) = 6mm (0.23622...), its NOT. OEM is 6mm.